[jira] [Created] (HDFS-15443) dfs.datanode.max.transfer.threads should have check code

["AMC-team (Jira)" <ji...@apache.org>]

AMC-team created HDFS-15443:
-------------------------------

             Summary: dfs.datanode.max.transfer.threads should have check code
                 Key: HDFS-15443
                 URL: https://issues.apache.org/jira/browse/HDFS-15443
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: datanode
            Reporter: AMC-team


Configuration parameter dfs.datanode.max.transfer.threads is to specify the maximum number of threads to use for transferring data in and out of the DN. This is a vital param that need to tune carefully. There are many bad cases that caused by not setting this param to an appropriate value.

{code:java}
// DataXceiverServer.java
// Make sure the xceiver count is not exceeded
intcurXceiverCount = datanode.getXceiverCount();
if (curXceiverCount > maxXceiverCount) {
thrownewIOException("Xceiver count " + curXceiverCount
+ " exceeds the limit of concurrent xceivers: "
+ maxXceiverCount);
}
{code}

However, there is no any check code to restrict the parameter. Although having a hard-and-fast rule is difficult because we need to consider number of cores, main memory etc, *we should at least prevent users from setting this value to an absolute wrong value by accident.* (e.g. a negative value that totally break the availability of datanode.)

*How to fix:*

Add proper check code for the parameter.



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